|What makes you think I can do that?|
This page contains conjecture or inductive logic about a subject that is not explicitly mentioned or explained in the canon.
A list of Supernatural inconsistencies that have occurred during its run.
- When an angel was killed, burnt wings would be appear on the ground next to the body. Beginning in Season 9, this effect was no longer used as all of the angels wings burnt off during the fall. However, in Meta Fiction many dead angels can be still be seen with their burnt broken wings. This affect wasn't seen again until Season 12 in Lily Sunder Has Some Regrets.
- The arrival of angels in 2009 sparked concern for the demons as angels had not officially been on Earth for maybe thousands of years. Anna Milton stated that her own garrison was forced to watch humans and not interact with them for 2,000 years. However, in Lily Sunder Has Some Regrets, it is revealed there was an angel garrison permitted to be on Earth only about 100 years ago. Castiel was a member of this garrison before joining Anna's.
- In Hell's Angel, Amara refers to Lucifer as the "first son", which is inconsistent with statements made by Michael and Lucifer throughout season 5, in which Michael is the first son and Lucifer is the second. It is unclear why Amara said this.
- Lucifer himself refers to Michael as his "little bro" in The British Invasion.
- In Free To Be You and Me, it was explained that after an archangel leaves his vessel, the vessel becomes paralyzed or worse. This depends on the archangel's strength as Castiel said: "Michael is much more powerful. It'll be far worse for you" to Dean. However, in LOTUS, after Lucifer was exorcised from Jefferson Rooney, the president was alive and healthy. However, this may be intentional on the Archangels' part, as Michael would later tell Dean that he wouldn't be a "drooling mess" after he's finished using him.
- Azazel fed demon blood to a number of babies who grew up and became Special Children for the purpose finding the perfect soldier to lead the demon army. Sam Winchester was the one he was rooting for, and he intended for Sam to win a battle against other Special Children of his generation.
- In All Hell Breaks Loose - Part 1, Azazel implied that he had fed demon blood to many other generations. This explains why Azazel sought out Rosie Holt, twenty-three years after Sam was born.
- In Lucifer Rising, it is revealed that Azazel created the Special Children in order to find a suitable vessel for Lucifer.
- Although it was widely known by the demons that Sam was Azazel's choice for the leader of the demon army, Lilith apparently did not know of the real reason for Azazel's decision, and made it her intent to kill Sam Winchester, going so far as to put out hits. Killing Sam would prevent Sam from fulfilling his role as Lucifer's vessel, and ruining Azazel's plan. Even worse, once Lilith took control over Hell, all demons Sam encountered from then on sought out to kill him. It's safe to assume that much of this happened because of Azazel's unexpected and premature death.
- In My Bloody Valentine, Castiel consumes hundreds of hamburgers and a tray of raw meat due to the influence of Famine. He tells Dean that the burgers make him "very happy" and his facial expressions imply that he finds they taste delicious. However, in First Born, Castiel complains that by becoming an angel again, he has lost the ability to taste food like a human, and a sandwich tastes like "molecules" to him. On a side note, if angels could not taste food like humans, then every drink and snack would taste like molecules, in other words, "disgusting", yet Gabriel and Balthazar are shown consuming human foods with no trouble in the taste.
- In Lily Sunder Has Some Regrets, Castiel is revealed to have been on Earth approximately 100 years ago with his former garrison in order to punish a fellow angel for breaking the rules. This is inconsistent with Castiel's statement in Are You There, God? It's Me, Dean Winchester, in which he tells Dean that angels did not walk among humans for 2,000 years prior to Dean's resurrection. This was cleared up after Castiel mentioned the special circumstances surrounding the situation, calling it an "anomaly". Sam also thought angels never came to earth prior to the apocalypse, before Castiel told him the story of the child they thought was a nephilim.
- In the Season 8 episode The Great Escapist, Sam recalls a visit to the Grand Canyon when he was four-years-old, however, Dean mentions in Season 2 episode Croatoan that they have never been to the Grand Canyon. Writer Ben Edlund admits this to be a mistake on his part.
- In Slumber Party, Charlie Bradbury goes to Heaven after being killed by the Wicked Witch of the West. However, it is revealed in Captives that Metatron's spell not only closed off Heaven to angels but also to souls as well. Charlie should have been stuck in the Veil like Kevin Tran was rather than going to Heaven.
- Lilith's plan for Season 3 and most of Season 4 seems to contradict her end plan to free Lucifer. For the entirety of Season 3 and most of Season 4, Lilith's plan was to kill Sam Winchester in order to rid herself of any opposition so she could claim the throne of Hell. She sent a number demons after Sam and personally attempts to kill him in the Season 3 finale, only to become scared when Sam proves immune to her powers.
- By the Season 4 episode The Monster at the End of This Book Lilith wants to make a deal with Sam and obtain his soul in exchange for escaping her fate as the final seal to Lucifer's Cage. Again, she makes an attempt to kill Sam, indicating she was pretending to offer a deal. By the Season 4's finale, she has submitted to her fate and lets Sam kill her as he was pre-destined to.
- This behavior is odd since Lilith had, pre-Season 3, ordered Ruby to act as a double agent and feed Sam demon blood so he would become powerful enough to kill Lilith anyway. Her motive for killing Sam appears inconsistent with her endgame.
- There seems to be an inconsistent statement regarding how Lucifer was cast into Hell and subsequently the Cage. It is initially said that God had been the one to banish Lucifer into his prison, though Season 5 reveals that Michael did it on God's orders following the conclusion of the First Heaven Civil War. Dean tells Rowena in O Brother, Where Art Thou? that God dumped Lucifer into the Cage himself, which is untrue.
- In Metamorphosis Dean and Sam first discover what a rugaru is from the hunter Travis. However, in Bad Boys a fourteen year old Dean, mentions his father is busy hunting a rugaru.
- In the past all shapeshifter transformations (excluding the alpha) involved the shapeshifter's skin getting peeled/ripped off. However, in Blade Runners, a shifter is shown to seamlessly transform without shedding its skin. This ability was seen again in Bloodlines. VFX I/O Coordinator Adam Williams revealed he was puzzled at why this was. "No idea.. I kinda wondered the same myself. Originally I assumed there were “skinwalkers” and “shapeshifters” and the skinwalkers shed their skin - then I read the superwiki and realized the Alpha can transform without a skin shed but they are all the same monster. I guess sometimes legacy changes." 
- In Stairway to Heaven, Reapers were retconned as being a type of angel. However this would mean that demons have the ability to possess angels as Azazel possessed Tessa in In My Time of Dying. This was backed up in season 11 when Crowley possessed Lucifer who was possessing Castiel in order to try and bypass the angel in control and talk directly to the vessel.
- Whenever he needed to contact a reaper, Dean would die temporarily, as seen in Death Takes A Holiday, Appointment In Samarra and Red Meat. However, this does not appear to be necessary, as Tessa and Billie have both appeared to Dean in the physical world, as well as an unnamed reaper in Faith. This implies that reapers can take vessels, just like other angels.
- Up until Season 11 finale Alpha and Omega, killing Amara has never been stated to cause any side effects. Prior to this, attempts have been made by Dean and the angels, though both have failed due to the power difference. It is mentioned that during the First War against the Darkness, God and the archangels did not destroy Amara simply because they were not powerful enough, and had to resort to tricking her and then imprisoning her.
- After God is weakened by Amara, the sun and plants begin to show signs of decay revealing that God and Amara must both co-exist or cease to exist in order to allow Creation to remain.
- Rob Benedict, who portrays God, revealed that this change of script was due to the network which airs Supernatural the CW, an early script draft revealed God was originally intended to die at the end of the season until CW intervened.
- The first five seasons take place in the current time, matching with the year the season was aired in. Season 5 concludes around May 2010. Between Seasons 5 and 6, a year has gone by during which Dean has been living with Lisa and Ben Braeden, and by the time Sam gets his soul back in Season 6 episode Like A Virgin, a year and a half has gone by since the Season 5 finale. This would put the date around November 2011. However, the Supernatural crew decided to resume their tradition of giving each season the same year it was aired in, leading season 6 to be marked with the year 2010. Assistant Director Kevin Parks explains this decision: "They decided to do 'soap opera time', because they didn't want to have to push the year forward for the rest of the show's run. So, just like in soap operas when people's kids are toddlers and then suddenly teenagers, so too can Sam and Dean spend a year apart while no time has actually passed in reality." The timing went back to normal after this with season 8 being both aired and set in 2012-2013, as proven by Henry Winchester travelling to 2013 in an episode that aired in January of that year.
- In Season 6 episode Appointment In Samarra, Death expressed his annoyance for the brothers' constant resurrections, as it disrupts the natural order, forcing him to clean up after them. However, in Season 11, Billie says that Death was amused by their resurrections.
- In Season 6, episode Mommy Dearest, Eve said that: "Each soul a beautiful little nuclear reactor. Put 'em together, you have the sun." However, Castiel said that each soul has the power of one hundred stars.